南宋古文評點為中國古代評點學的開端，其揭示文章之「關鍵」，建立首尾、布置、鋪陳、間架、回互、抑揚、開合、反覆、繳結、關鎖、頓挫、曲折、筆力、節奏等核心術語，以分析、呈現文章結構脈絡、相應往復的關係。本文以為「關鍵」即是「文法」，文中大致考察六朝以來體式／體勢、文氣／氣勢說，以闡述古文評點「文勢」之美學意涵，發現無論氣勢或體勢皆須文法斡旋其中，「文法」與「文勢」相通相融，兩者互為涵攝，進而建立曲折變化，且富有筆力、節奏的古文美學。

The Southern Song dynasty marks the beginning of Chinese study on the marginalia of ancient proses. It was then when ＂crucial＂ literary theory and terms were established to analyze the structure and coherence of writings. This paper analyzes the theory established since the Six Dynasties in regard to tishi and qishi , as well as their related critical terms, and finds that ＂crucial＂ literary theory for the marginalia in ancient proses in fact combine ＂wenfa＂ and ＂wenshi＂, two concepts that are closely intertwined. Tishi focuses on the construction and layout of the whole piece of writing, while qishi emphasizes the forms of individual sentences. To put these two together allows one to better understand the characteristics of ancient marginalia criticism, and to discover the aesthetics of ancient proses, which is full of twists and turns, as well as powerful rhythm.